Brake for forming metal plate and sheet



Feb. 26, 1963 P. 1.. CADY, JR

BRAKE FOR FORMING METAL PLATE AND SHEET 4 Sheets-Sheet 1 Filed Sept. 1, 1961 INVENT R.

ATTORNEYS.

Feb. 26, 1963 P. L. CADY, JR 3,078,903

BRAKE FOR FORMING METAL PLATE AND SHEET Filed Sept. 1, 1961 4 Sheets-Sheet 2 Q ive & t

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ATTORNEYS.

Feb. 26, 1963 P. CADY, JR

BRAKE FOR FORMING METAL PLATE AND SHEET 4 Sheets-Sheet 5 Filed Sept. 1, 1961 ATTORNEYS.

Feb. 26, 1963 P. CADY, JR

BRAKE FOR FORMING METAL PLATE AND SHEET Filed Sept. 1, 1961 4 Sheets-Sheet 4 3.073393 BRAKE FOR FGRMING METAL PLATE AND SHEET Percy L. Cady, .lrz, Darien Center, NY. Filed Sent. 1, 1961. Ser. No. 135,674 4 Claims. (Cl. 153-16) This invention relates to a brake for forming metal plate and sheet having a pair of forming aprons or wings swingable about a common forming axis which is adjacent and parallel with the working surfaces of the aprons and which brake also includes a mandrel movable toward and from the forming axis and around which the aprons or wings bend the metal plate or sheet.

The invention forming the subject of this application is an improvement on the brake shown in the Cady application, Serial No. 8,603, filed February 15, 1960, now Pat. No. 3,044,526, and in common with said application important general objects are to provide a brake which is adapted to the production of a wide variety of forms by virtue of the ability to adjust the wings independcntly of each other with reference to the forming axis; which is simple and rugged in'construction but capable of very fine adjustment; which can be power operated and readily set to semi-automatic operation to facilitate the successive production of identical forms, and which will stand up under conditions of severe and constant use without getting out of order or requiring repairs.

A specific object of the present invention is to avoid the production of defective products due to the workpiece slipping during the operation of the aprons or wings thereon, or due to the mandrel being bent horizontally out of alinement with the forming axis by the operation of the aprons or wings.

Another specific object of the invention is to avoid damage to the mandrel from unbalanced pressures imposed upon the mandrel by the workpiece in response to the operation of the aprons or wings.

These specific objects are achieved by controlling the initial movement of the aprons relative to each other and to the mandrel so that neither can proceed beyond a predetermined angularity until the other apron has reached a substantially similar vangularity. This control insures the production of an initial shallow channel in the workpiece, the sides of which rise along both sides of the mandrel. be further advanced independently of the other apron without danger of causing the workpiece to slide under the mandrel or without danger of the mandrel being bent laterally, and possibly broken because both the mandrel and the workpiece are held securely in proper relation to the forming axis by virtue of the shallow groove, with its opposite rising sides, holding the workpiece in fixed relation to the mandrel.

Other objects and advantages of the invention will be apparent from the following description and drawings in which:

FIG. 1 is a front elevational View of a brake for metal plate or sheet embodying the present invention.

FIG. 2 is a view similar to FIG. 1 but with parts broken away to illustrate operating mechanism contained within the end columns of the brake frame.

FIG. 3 is an end elevational view, viewed from the right hand ends of FIGS. 1 and 2.

FIG. 4 is an enlarged vertical fragmentary section taken generally on line 44, FIG. 2.

PKG. 5 is a fragmentary enlarged vertical section taken generally on line 5--5, FIG. 2.

FIG. 6 is an enlarged fragmentary front elevational I FIG. 7 is a fragmentary view similar to FIG. 4- illus? trating how the workpiece or the mandrel could be bent out of true without the practice of the present invention.

FIG. 8 is a diagram of the hydraulic circuit and showing a simplified diagram of the electrical components.

The brake of the present invention is an improvement on the brake described and disclosed in detail in the said Cady application, Serial No. 8,603, filed February 15, 1960, now Patent No. 3,044,526, and reference is made to this copending application for a more detailed description of the identical mechanical components of the brake.

The frame of the sheet metal brake comprises a pair of end columns or stands indicated generally at 39 and connected at their lower ends by a horizontal beam 31 and at their upper ends by a horizontal beam 32. Each of the columns 36} has a rectangular base plate 33 welded to and supporting a main or backbone plate 34 of the column. This main plate 34 of each column is reinforced along its front and rear vertical edges by flanges 35 and 36 so as to provide a post which is of channel form in horizontal cross section opening outwardly as best shown at the left of FIG. 2.

When this condition obtains either apron can In addition the main or backbone 34 of each column is reinforced by triangular gussets 33 the bottom edges of which are welded to the base plate 33. Each bottom plate 33 also has welded thereto an upstanding plate or bar 39 to which the ends of the lower bottom cross beam 31 are suitably secured in any suitable manner.

Each column 36 also includes an upper box portion indicated generally at 4%, these box portions being secured to the upper parts of the main or backbone plates 34 in opposing relation to each other. Each box portion 3% comprises a rear plate 41 and a front plate 42, these plates being secured, as by welding, to the front and rear edges, respectively, of the main plate 34 of each column. The outboard or opposing edges of these plates 41,- 42 are connected by a cross plate 43 so as to complete the box section.

The top of each box portion 46 is enclosed by a block '44- secured therein in any suitable manner and to which blocks the opposite ends of the upper cross beam 32 are secured. A horizontal cross plate 45 connects the bottom edges of the rear and front plates 41, 42 of each box portion til, the plates 43 projecting downwardly below these horizontal cross plates. The depending end of each of these plates 53 carries a boss 46, these bosses being in horizontal coaxial alinernent with each other and with bosses 48 on the main plate 34 of each column 49. The bosses 56, 48 of each column 30 carry the main pivot pin 49 of the brake, each main pivot pin also being supported at its center in a plate 56' depending from the center of the corresponding horizontal cross plate 45 as best shown in PEG. 2

The main pivot pins 49 support the knuckles of rear and front aprons indicated generally at 51 and 51a as hereinafter described, these aprons cooperating with a clamping ram indicated generally at 53 in bending a plate or sheet of metal 55 (FIG. 7) to the desired form, this figure illustrating how the workpiece should not be formed. This clamping ram 53 includes a holder in the form of a vertical plate or beam 54 arranged directly above and parallel with the axis of the main pivot pins 49 and having its opposite ends protruding through openings 56 in the plates 53 into the interiors of the box portions iii of the end columns 35 of the brake frame.

Within each column 3% of the brake frame, the corresponding end of the plate or beam 54 is guided for vertical movement toward and from the axis of the main pivot pins 43 between a pair of slide guides 58 on the opposing faces of the rear and front plates 4-1, 42 of each end column 3% of the brake frame, as best shown in .3 FIG. 2. The plate or beam 54 is held against endwise displacement by having a brass liner 60 secured to each of its ends and engaging a slide guide 61 secured to the main or backbone plate 34 of the corresponding end column as best shown in FIG. 2.

Hydraulically or pneumatically actuated means are provided for moving the opposite ends of the clamping ram 53 vertically into and out of engagement with the work piece 55 on the two aprons 51, 51a, these means preferably being constructed as follows:

The numeral 65 represents an ear secured to and projecting from the exterior face of the main backbone plate 34 of each end column 30. To each of these cars is pivoted the lower end of a cylinder 66 containing a piston 68 including a piston rod projecting upwardly from the cylinder. A pivot block 69 is fixed to the upper end of each piston rod 68 and this block 69 is interposed between the generally horizontally projecting arms 70 of a corresponding pair of bell crank levers 71, the other generally vertically projecting arms of which are indicated at 72. The arms 72 of the bell crank levers 71 are housed within the box portions 49 of the end columns 30 of the frame and the arms 70 project outwardly through openings 74 in the main or back-bone plates 34 of these columns. The outer ends of the arms 70 are connected to the blocks 69 by pivot pins 75 and within the box portions 46 the bell crank levers 71 are supported at their centers by large pivot pins 76. Each pivot pin 76, is journalled in a bearing in the stem of a screw 80, the ball crank levers 71 being arranged on opposite sides of the shank of the screw. Each pin 76 is guided for vertical movement in the manner disclosed in detail in the said Cady application. Accordingly, vertical movement of the horizontally projecting arms 70 of the bell crank levers by the piston 68 effect horizontal movement of the arms 72 thereof, these last arms forming one side of a toggle linkage connecting with the corresponding end of the plate or beam 54 of the clamping ram 53. For this purpose, the lower ends of the arms 72 of each pair of bell crank levers 71 embrace the upper end of a toggle link 84 and are connected thereto by a pivot pin 85. The lower end of the toggle link 84 is interposed between a pair of ears 86 to which it is connected by a pivot pin 88. Each pair of cars 86 is fixed to and pro: jects upwardly from the corresponding end of the plate or beam 54 of the clamping ram 53.

Means are provided for adjusting the working position of the clamping ram 53, these means being preferably constructed as follows:

The numeral 90 represents a hand crank suitably jourualled on the column 36 at one end of the brake and turning a pinion 91 connected by a drive chain 92 with a pinion 93 at one end of an adjusting shaft 94 suitably journalled on the upper end of that column. One end of this shaft 94 is connected by a releasable coupling or jaw clutch 95 with a shaft 96, the opposite end of which is suitably journalled at the other end column 39 of the machine. The coupling 95 can be manually connected or disconnected in the manner disclosed in detail in said Cady application.

Above each end column 30, the corresponding shaft 94 and 96 carries a worm 110 which is fixed thereto and which meshes with a worm wheel 111. The latter is suitably secured as by the screw 112 shown in FIGS. 1, '2 and 3, to the upper end of a nut 114 journalled to rotate about a vertical axis in a bearing 115 in the block 44 at the upper end of each column 39. Each nut is threadedly connected with the upper threaded end of the corresponding screw 80.

The workpiece is engaged by a mandrel 120 removably secured to the bottom of the plate or beam 54 of the clamping ram 53. The mandrel is shown as being in the form of a rectangular blade having a rounding bottom longitudinal nose portion 121engaging the workpiece 55. The upper edge. of this blade is shown as clamped in a rabbet 122 along the lower edge of, the beam or plate 54 of the clamping ram 53 by means of a plurality of clamping plates 123 clamped against the upper end of the blade 12! by means of a plurality of screws 124. It will be seen that in deforming a workpiece held down on the aprons 51 by the mandrel blade 120, it is important that the forming pressures be balanced so as not to displace its nose 121 laterally.

Each of the two aprons 51, 51a, on which the workpiece 54 is clamped by means of the mandrel can be of various construction but is shown as an example as constructed as follows:

Each apron 51, 51a includes a wing in the form of a large metal plate extending lengthwise of the mandrel 120 and at the start of the forming operation these wings or plates are arranged in closely spaced vertical face-to-face relation, as shown in FIG. 4, on opposite sides of a plane intersecting the forming axis of the mandrel 120 which is at the center of its rounding nose 121. Both wings have ends of reduced height and the wing at the rear of the rake is designated at 125 and the wing at the front of the brake is designated at 12511, the latter being somewhat longer than the former. Along the upper edge of each wing 125, 125a, a reinforcing angle bar 126 is se cured, as by screws 127, to its outer face, these angle bars extending the full length of the wings and each clamping a forming blade 128 to the top of each wing. For this purpose, each forming blade 128 is L-shaped in cross section and is clamped in a rabbet 129 along the upper edge of each wing. The working surfaces of these forming blades 128 face upwardly.

Each apron 51, 51a is preferably independently pivoted on the main pivot pins 49 and are also independently adjustable toward and from the forming axis by means which are preferably constructed as follows:

The numeral 130 represents a square nut fixed to each end of each wing or plate 125, 125a on the outer face thereof, these nuts being arranged parallel with one another and in planes perpendicular to the forming axis. A screw 138 works in each nut 130, these screws being rotatably mounted on pins 139, the inner end of each of which pins being fixed in a hinge arm 141 having a pair of knuckles 1 42 journalled on the corresponding main pivot pin 49 as best shown in FIG. 2. As shown in this figure, the knuckles 142 of the front apron 51a are arranged in alternation to the knuckles 142 of the rear apron 51.

Each screw 138 is pinned, as indicated at 144, to a worm wheel 145, these worm wheels being arranged in a common horizontal plane in the upright position of the aprons 51, 51a. To prevent lengthwise movement of each screw 138 and its worm wheel 145 lengthwise of the corresponding pin 139, a collar 146 is pinned to the outboard end of each pin 139 to engage the corresponding worm wheel 145. The opposite end of each screw 13 8 rotatably engages the corresponding hinge body 141 and preferably has an enlarged annular flange 148 interposed between this hinge body 141 and its nut 130 and bearing a series of graduations 149 so that the angular position of each screw 138 can be determined by reference to the scale provided by these graduations 149. This scale provides a fine adjustment scale for the position of each screw 138, thereby to determine, with a high degree of accuracy, the axial position of each nut 130. A coarse scale for the position of each apron is provided by a bar 150 secured to each not 130 to project upwardly therefrom and bearing a series of graduations 151 arranged to traverse a reference point (not shown) on the corresponding hinge body. 141.

As previously indicated, the worm wheels 145 are adapted to be brought to a common horizontal plane and when brought to this position, each engages a worm 155 fast to an adjusting shaft 156. This adjusting shaft extends the full length of the brake and is journalled iu bearings 158, 159 on the end columns 39 of the frame- This shaft has fixed thereto a sprocket 160 connected by a chain 161 with a sprocket 1:62 fast to the crankshaft 163 of a hand crank 164. It will be seen that turning the hand crank 164 turns the shaft 156 and its worms 155, thereby to turn the worm wheels 145 engaging these worms and hence the corresponding screws 133.

Means are provided for swinging the aprons 51, 51a independently of each other on the main pivot pins 4%, these means being preferably constructed as follows:

The numeral 165 represents an ear fast to and projecting outwardly from each nut 13%. To each ear is pivotally connected, as indicated at 166, the piston 168 contained in a cylinder 169. The piston and cylinder for the rear apron are distinguished by the suffix a. The upper end of this piston is pivotally connected, as indicated at 179, to an car 171 fixed to and projecting outwardly from the corresponding plate 43, 42 of each end column 33.

For repeated operation of the brake in the production of identical forms, it is desirable that each apron 5-1, 51a be individually stopped at the angular position required so that the operator has merely to place the workpiece 55 in position, clamp the workpiece against the aprons 51, 5111 by the mandrel 12%, and start the operation of these aprons, the aprons automatically stopping when the workpiece is bent to the required form. The mechanism for accomplishing this is preferably constructed as follows:

The numeral 190' represents a segmental plate fast to the exterior of one knuckle 142 of each apron S l 51a, this being at the right hand end of the brake as viewed in FIGS. 1 and 2. As best shown in PEG. 5, a Wire 1191 is fixed to the leading edge of each of these segments so that as each apron 51 or 51a is swung about the main pivot pins 49, the corresponding wire 191 is moved longitudinally proportionally. Each wire 191 passes around pulleys 19-2 (FIGS. 1 and 5) to the top of the adjacent column 39 of the frame and thence downward along the side of this column behind a cover plate 193. The other end of each wire 1911, as best shown in FIG. 11, is secured to a vertically reciprocating rod 194, these rods being mounted for this purpose in stationary slide bearings 195. Weights 1% are secured to the lower ends of the rods 1% and a sleeve 1% is adjustable along each of these rods. The upper end of each sleeve is in the form of a square head 19% carrying a set screw 2% having a handle by means of which the set screw can be reeased to free the corresponding sleeve 1% for adjustment vertically along its rod 194, the sleeves being guided in stationary slide bearings 282. Each set screw 2% extends through a vertical slot 2% in the cover 193 for ready accessibility of its handle and the cover 193 is also provided between these slots with another vertical slot 2% through which a graduated scale 2% is visible. This scale is calibrated in degrees of angularity up to 90 and is traversed by a pointer 2% on the square head 1% of each of the sleeves 1%.

Each of these sleeves 198 carries a stop in the form of a earn 2% operating an electrical switch, the switch for the rear apron being designated at 21th and the switch for the front apron being designated at 216a.

An important feature of the invention resides in each rod 194 additionally carrying a vertically elongated cam bar 211 in position to engage, actuate and hold the arm of a switch, the switch for the ear apron being designoted at 212, and the switch for the front apron being designated at 2 12a. Each cam bar 211 is arran ed to engage and actuate its switch 212. or 222:: when the corresponding apron has reached an angularity of approximately with reference to the horizontal. The essential functioning of these switches is to arrest either apron when it reaches such 15 position until the other apron reaches a substantially similar position, following which these switches permit completion of the movement of the aprons as determined by the settings of the cams 2929 with reference to the switches 21% and 210a, as well as permit the return movement of the aprons.

Referring to the hydraulic circuit, FIG. 8, the numeral 215 designates a motor driving a pair of hydraulic pumps 2'16 and 2-18 drawing oil from a supply 219. The pumps 216, 2,18 deliver the oil through lines 2269 and 221, respectively, to a common line 222 delivering the oil to a three position spring centered solenoid valve 223. The lines 2126 and 221 contain check valves 224 and 225, respectively, opening in the direction of oil flow from the pumps and the line 22th contains a relief valve 226 returning oil under excess pressure to drain 228. The common line 222 contains a relief valve 22s returning oil under excess pressure to drain 223.

In the centered position of the three position valve 223 the supply line 222 connects with a port 2-3'1) providing communication with a line 23ft having a branch 232 leading to a solenoid valve 233. In the deenergized condition of this solenoid valve, the line 232. is connected by port 234 to drain 2 28. In the energized condition of this solenoid valve the flow of oil from the line 232 to drain is cut off, this line being provided with a relief valve 235 discharging to drain 228 under excess pressure.

The spring centered three position solenoid valve 223 is moved to one extreme position to move the clamping ram 53 into engagement with the workpiece by energizing its solenoid 236. This can be done by a sv itch 237 actuated by the operator. When the solenoid 236 is so energized, the oil supply line 222 is connected by port 238 to a line 239 connected by flexible hoses 24-63 to the lower ends of the clamping cylinders en. The line 239 contains a relief valve 244. discharging to drain 228. Also when the solenoid is so energized, port 242 connects the line 231 with a line 2 53 connected by flexible hoses 244 with the tops of the upper ends of the clamp cylinders 65 to permit the escape of oil therefrom.

The spring centered three position solenoid valve 223 is moved to its oth r extreme position to move the clamping ram 53 out of engagement with the workpiece by energizing its solenoid 245. This can be done by a switch 246 actuated by the operator. When this solenoid 245 is so energized, the oil supply line 222 is connected by port 249 to the line 243 and the line 239 is connected by port 25% to the line 231.

The pistons 2168, 168a of the two aprons 51, 51a are selectively actuated by oil supplied from the line 231 by substantially identical hydraulic and electrical circuits, and hence a description of one will be deemed to apply to both the components of the hydraulic and electrical circuit for the front apron being distinguished by the suflix a. Each of these hydraulic circuits is preferably constructed as follows:

The numeral 255 represents a branch line containing a check valve 256 and leading to a three position spring centered solenoid valve indicated generally at 258. In the spring centered position of this solenoid valve, all lines connected with the valve are blocked as shown.

Each spring centered three position solenoid valve 258 is moved to one extreme position to effect operative movement of the apron 51 by energizing its solenoid 259. This can be done by means of a switch 260, the two solenoids 259, 25% also preferably being in series with the solenoid 261 of the valve 233 by means of a branched electrical line 262 so that energization of either solenoid 2559 or 25% will also effect energization of the solenoid 261 of the valve 233. When the solenoid 259 is so energized, oil from the branch line 255 is conducted by port 263 to a line 264 connected by flexible hoses 265 with the bottoms of the cylinders 169. Each line 264 contains a check valve 2'70 opening toward the cylinders 169. Also when the solenoid 259 is so energized, a port 271 connects the line 2'72 from the top of the cylinders 169 with drain 22%. The line T2 is connected to the top of the pair of cylinders 169 by flexible hoses 273.

Each spring centered three position solenoid valve 258 aoeaeos is moved to its opposite extreme position to etlect return movement of the aprons 51 by energizing its solenoid 274-. Provided the switch 212 permits, this can be done by the switch 216 which also simultaneously energizes the solenoid 261 of the valve 233 through the branched line 262. When solenoid 274 is so energized branch line 255 is connected by port 276 with line 272. A regenerative circuit line 267 connects the line 264, between the cylinders 169 and check valve 270, with the line 255, between the three position solenoid valve 258 and the check valve 256.

A globe valve 278 is provided between lines 264 and 272 to permit slow movement for setting up the aprons. Likewise a globe valve 279 can be provided between lines 239 and 243 to permit slow movement for setting up the clamping ram 2553.

The present invention is essentially concerned with the switches 212 and 212a which respectively control the travel of the aprons or wings 51, 51a during approximately their first of movement upwardly and outwardly from their face-to-face position illustrated in FIG. 4, in such manner that neither wing or apron can swing beyond this approximate 15 position until the other wing has reached this position. For this purpose the switch 212 (FIG. 6) which is moved in response to the cam bar 211 moving in synchronism with the rear wing 51, has a pair of movable contacts 280 and 281 (FIG. 8) which are coupled to move together, these contacts being moved upwardly from the positions shown in FIGS. 6 and 8 when the cam bar 211 of the wing 51 engages and lifts the contact 280. Similarly, the switch 212a (FIG. 6) which is moved by the cam bar 211 moving in synchronism with the front wing or apron 51a has a pair of movable contacts 284 and 285, these contacts being moved upwardly from the positions shown in FIGS. 6 and 8 when the cam bar 211 associated with the wing 51a engages and lifts the contact 284.

The movable contact 280 is permanently connected to a wire 286 one end of which connects with the side of the solenoid 259 opposite from that connected with the wire 2fi2 and the other end of which wire 263 connects with the movable contact 285 of the switch 212a The movable contact 281 engages a fixed contact 290 permanently connected by a wire 287 to the fixed contact 288 engaged by the movable contact 284 of the switch 212a, this fixed contact 288 also connecting with the switch 262a The movable contact 284 is permanently connected to a wire 289 one end of which connects with the side of the solenoid 259a opposite from that connected with the line 262 and the other end of this wire 289 connects with the movable contact 281 of the switch 212. The fixed con tact 291 engaged by the movable contact 280 of the switch 212 connects with the switch 269 and also via a wire 292 with the fixed contact 293 engaged by the movable contact 285 of the switch 212a.

Operation In this description of the operation of the brake, it will be assumed that a metal plate is to be formed into an angle around the rounding nose 121 of the mandrel 128. It will also be assumed that the motor 215 is running and driving the pumps 216 and 218.

In producing an angle from the plate 55, the forming axis is the center of the rounding nose of the mandrel 129 and this forming axis must be coincident with the axis of the main pivot pins 49 on which the aprons 51, 51a swing. In the event that it is necessary to raise or lower this forming axis to effect such coincidence, the height of the mandrel is adjusted by turning the crank 90, FIGS. 1, 2 and 3, through the chain 92, turning the sprocket 93 fast to the adjusting shaft 94. Assuming that it is desired to adjust both ends of the mandrel 126 uniformly, the coupling 95, FIGS. 1 and 2, would remain coupled during this adjustment so that the shaft 96 turns with the adjusting shaft 94, thereby to turn both worms 110 at the same rate. Accordingly both worm wheels 111 are turned in unison, thereby to turn the nuts 114 and raise or lower the screws 86. Vertical movement of these screws effects vertical movement of each of the toggles 72, 84 and the clamping plate or beam 54 together with the mandrel 12h suspended therefrom.

If it is desired to adjust one end of the mandrel higher than the other, or to correct any such differential, the left hand end of this mandrel, as viewed in FIGS. 1 and 2 is adjusted to the proper height as above described, the clutch or coupling 95, FIGS. 1 and 2 is uncoupled, and the crank 90, FIGS. 1, 2 and 3 is then turned in the proper direction, this turning only the adjusting shaft 94, FIG. 2, thereby to turn the worm wheel 111 at the right hand end of the brake, as viewed in FIGS. 1 and 2 to the exclusion of the worm wheel 111 at the other end of the brake. Accordingly, only the nut and screw adjustment 114, 89 at this right hand end of the brake will be actuated and hence only the corresponding end of the mandrel 120 will be raised or lowered.

The working surfaces or forming blades 128 of the aprons 51, 510 are adjustable with reference to the forming axis to adjust the brake to the thickness or form of the workpiece 55, this forming axis as above described being coincident with the axis of the main pins 49 for these aprons. Assuming it is desirable to adjust both aprons 51, 51a uniformly in this regard, as for a particular thickness of the workpiece 55, this adjustment is efiected by turning the crank 164, FIGS. 1, 2 and 3, thus, through the chain 161 turning the sprocket 169 fast to the shaft 156 carrying the worms 155. These worms, in the pendent position of the aprons 51, 51a, engage the worm wheels 145, FIGS. 1, 2 and 4, so as to turn these worm wheels and the screws 138 pinned thereto. Each screw 138 is rotatably secured, but held against longitudinal movement with reference to the knuckle 141 at each end of each apron and hence this rotation of these screws 138 serves to move the sleeve nuts longitudinally. Since these sleeve nuts are secured to the wings or plates 125, 12511 of the aprons 51, 51a, this adjusts these wings or plates the forming blades 128 carried thereby, with reference to the forming axis. The coarse adjustment of each apron 51 or 51a can be seen at each end on the scale on the upstanding rod on each sleeve nut 130 and the fine adjustment of each apron can be seen on the scale 149 around the top of each sleeve nut 130.

After such adjustment and with the clamping plate or beam 54 and its mandrel 120 in elevated position, the workpiece 55 is placed upon the aprons 51, 51a as shown in FIG. 7.

With the motor 215 and pumps 216, 218, FIG. 8, running, oil at this time is being supplied under pressure from the source 219 through the lines 220 and 221 to the common line 222, this oil passing through the port 230 of the now spring centered three position solenoid valve 223 to the line 231 and thence through the port 234 of the deenergized solenoid valve 233 to drain 228.

The operator first brings the clamping ram 53 down to cause the nose 121 of the mandrel 120 to clamp the workpiece 55 against the forming blades 128 of the aprons 51, 51a. He does this by closing the electrical switch 237. This energizes the solenoid 236 so as to shift the spring centered solenoid valve 223 so as to connect its port 238 with the lines 222 and 239 and its port .242 with the lines 243 and 231. Accordingly, oil under pressure from line 222 flows through port 238 and line 239 into the bottoms of the cylinders 66 thereby to project the pistons 68. The oil at the opposite sides of these pistons 68 is relieved through the lines 243, port 242, line 231 and solenoid valve 233 to drain 228.

This projects the pistons 68 thereby to swing the bell crank levers 71 about the pivot pins 76. The end 72 of each of these bell crank levers form one side of a toggle linkage '72, 84 which forces the clamping ram 53 down wardly in response to this projection of the pistons and piston rods 63. In this movement the clamping ram 53 is guided against lateral displacement by slide guides 58 (FIG. 2) and against endwise displacement by the slide guides 61. This action of the pistons 68 is in the cylinders 66, through the bell cranks 71 and toggle links 72, 84, brings the forming axis of the mandrel 12% (center of its nose 121) into concentricity with the axis of the main pivot pins 49 and the nose 121 of the mandrel against the top of the workpiece 55 to clamp it down on the aprons 51, 51a. When the pressure supply to the spring centered solenoid valve reaches the setting of the unloading valve 226, the output from pump 216 is unloaded through this unloading valve 226 to drain and the clamping pressure is determined by the setting of the unloading valve 226.

Since both the mandrel 129 and its supporting beam or plate 54 are of relatively thin plate-like form, it is apparent that they would be subject to lateral distortion if unbalanced pressures were initially applied by the aprons 51, 51a. Accordingly, it is desirable that during the first 15 or so upward movement of each of these aprons in bending the workpiece 55, that they be coupled together, in particular that neither wing nor apron exweds this approximate 15 movement until the other wing or apron has reached a substantially similar angular position.

In the normal operation of the brake, the operator would press and close both of the switches 26% and 26% to initiate the simultaneous initial upward movement of both aprons 51 and 51a to their 15 positions and beyond. So closing this switch 260 energizes the solenoid 259 of the spring centered solenoid valve 258 so as to bring its port 263 between the lines 255 and 264 and so as to bring its port 271 between the line 272 and the drain 228. This circuit so energized by the closing of the switch 269 comprises the switch 26%, fixed con-tact 291 and movable contact 280 of switch 212, wire 2-36, solenoid 259 and Wire 2622 through the solenoid 261 to the other side of line. Accordingly, so closing this switch ass also energizes the solenoid valve 233 so as to move its port 234 out of register with the line 232 and drain 22% and hence devent this last line to direct oil through the valve 253. Accordingly, oil under pressure from the branch line 255' of the oil supply line 231 flows through port 253 and line 264 to the bottoms of the cylinders its? so as to retract their pistons and piston rods 16%. At the same time, il on the opposite sides of these pistons escapes through line 272 and port Zill to drain 228. As a result the apron 51 is raised.

Again, when the pres-sure of the unloading valve 226 is reached, the output of pump 216 is again unloaded through this valve to the drain 228 and only the pump 218 is operative.

It has been assumed that the operator simultaneously closes switches 260 and 26% and with such closing of the switch 26th: the spring centered solenoid valve 258:; is actuated in the same manner as closing the switch 260 actuates the spring centered solenoid valve 253. Thus, so closing the switch 26% energizes the solenoid 259a of the spring centered solenoid valve 258a so as to bring its port 263a between the lines 25%;; and sea-a and so as to bring its port 271:: between the line 272:: and the drain 228. This circuit so energized by closing of the switch 26% comprises the switch 269a, fixed contact 38 and movable contact 234 of switch 212a, wire 28.9, solenoid 259a and wire 262 through the solenoid 261 to the other side or" line. Accordingly, so closing the switch 26% also energizes the solenoid 233 so as to move its port 234 out of register with the line 232 and drain 223 and hence devent this last line to direct oil through the valve 258a. Accordingly, oil under pressure from the branch line 255a of the oil supply line 231 flows through port 263a and line 264a to the bottoms of the cylinders 16% so as to retract their pistons and piston rods 16-8. At

10 the same time, oil on the opposite sides of these pistons pass through line 272a, and port 271a to drain 228. As a result, the apron or wing 51a is elevated along with the wing or apron 51.

When both rising aprons 51, 51a reach the assumed 15 angular position with reference to the horizontal, their bars 211 (FIG. 6) simultaneously engage and move the movable contacts 280 and 234 of their switches 212 and 212a, respectively. This, of course, breaks the above circuits but these circuits are immediately re-established by the closing of the movable contacts 281 and 285 which are respectively coupled to move with these movable contacts 28d and 284. Thus, the now open contact 286* is bypassed by the wire 292, fixed and closed contacts 293 and 285 of the switch 212a and wire ass so that the energization of the solenoid 259 is continued to hold the spring centered solenoid valve 258 in posit-ion to maintain the dew of oil to the bottoms of the cylinders lost in lifting the aprons 51. Similarly, the now open contacts 234 and 233 are bypassed by the line 237, closed contacts 281 and 2% of the switch 212 and line 239 so as to maintain the solenoid 259 energized and thus continue to hold the spring centered solenoid valve 289:: in position to deliver oil to the bottoms of the cylinders 169a and continue the rising movement of the apron or wing 51a.

Assuming that the final product from the workpiece 55 is to have a 99 bend, each apron 51, 51a would produce a 45 bend with reference to the horizontal and to produce such 45 bends by both aprons 51, 51a the pointers 2638, FIG. 6, will have been each set to 45 on the scale 2%. This is done by loosening the set screws 2% for each sleeve 198 and moving each sleeve vertically until its pointer 2&8 is in register with 45 on the scale 2% following which the set screw 2% is retightened. With such adjustment of the sleeves 193 with reference to the wires 19:. which wind around the segments 1%, FIG. 5, on the knuckles of the two apron'sfil, 51a, as these aprons reach their 45 position, as illustrated in FIG. 11, their wires 1% move their sleeves 198 to a posit-ion where their stops or cams 2h? trip the two switches Zdt 21%, FIGS. 6 and 8.

When this occurs the solenoids 274 and 2740 are energized to connect the oil supply lines 255 and 255a to the lines 2'72 and 272a, respectively, the closing of these electrical switches 21%, Elihu also energizing the solenoid 2-61 of the solenoid valve 233. This establishes a regenerative circuit to permit the aprons 51%, 51a to return on the effective area of the piston rods 163, Edda. Thus, pressure so established on the inlet side of the solenoid valves 253, 2538a is app-lied through ports 276, 276a and lines 2723, 2720, respectively, to the full area sides of the pistons 169, 16%. This oil is in part supplied from the piston rod sides of these pistons through the lines 264, 264:: and 267, 267a. Holding circuits and limit switches (not shown) are of course provided'to complete the return movement of the aprons 551, 51a and to de energize the solenoids 261, 274, 274a at the completion of the return movement of those aprons, a simplified electrical circuit being illustrated for clarity.

The operator then opens the switch 237 and closes the switch 246. Accordingly, the solenoid Z45is energized to move the spring centered solenoid valve 223 to conuect the lines 222 and 243 through the port 24% and to connect the lines 239 and 231 through the port 25%. Accordingly, oil under pressure flows from line 222 through port 249 and line 243 to the top sides of the cylinders ss to move the pistons 68 downwardly. The oil from the undersides of these pistons-escapesthrough the line 239, port 250, line 231 and port 234 of solenoid valve 233 to drain 228.

This moves the outboard arms 70 of the bell crank levers 71 downwardly to lift the clamping ram 53 through the link 84. Accordingly, the mandrel 126' is lifted from the clamping engagement with the workpiece 55, a complete sequence of the operation-0f the brake having completed and the parts being returned to the position assumed at the start of the description of operation.

The feature of the present invention resides in the provision of the switches 212 and 212a to prevent either apron from going beyond approximately a angular position before the other apron has reaced such position. This could occur if the operator should close, say, the switch 260 but fail to close the switch 260a. Under such a circumstance, the wing or apron 51 would, if not prevented by the switches 212 and 212a, continue to rise with the other apron 51a still in its bottom position and on exceeding the 15 angularity at the left side, as illustrated by the dotted line position of the workpiece 55 in FIG. 7, would exert sidewise pressure on the workpiece 55 which would be unopposed at the other or righthand side of the mandrel 120. As a result, the workpiece could slip sidewise under the nose 121 of the mandrel to result in an imperfect product. Also, since the mandrel 120 is in the form of a vertical blade, the mandrel can easily be bowed or bent laterally to the right, again resulting in an imperfect workpiece. Such strain on the mandrel could also break or put a permanent bend in it.

To avoid this, assuming the operator closes the switch 260 but fails to close the switch 260a, when the wing or apron 51 reaches a 15 angular elevation, its cam bar 211 (FIG. 4) engages and moves the movable contact 280 of the switch 212 so as to cause this contact (FIG. 8) to leave the contact 291 and the movable contact 281 coupled therewith to engage the contact 2%. Breaking the circuit through the movable and fixed contacts 280 and 291 deenergizes the solenoid 259 so that the spring centered solenoid valve 258 returns to its centered spring loaded position illustrated in which the lines 264 and 272 to and from the cylinders 169 for the apron or wing 51 are blocked off so that this wing is held in this 15 position.

The operator, observing the brake coming to a halt, now closes the switch 260a which he inadvertently failed to close. This establishes a circuit through the now closed contacts 288 and 284 of the switch 212a to energize the solenoid 259a and shift the spring centered solenoid valve 258a to admit oil to the bottoms of the cylinders 169a and lift the wing 51a, all as previously described. When the wing 51a reaches the assumed 15 position, through its cam bar 211 it lifts and opens the movable contact 284 of the switch 212a but this does not interfere with the continued upward movement of the apron or wing 51a because the now closed contacts 281 and 290 bypass this opened contact 284 and maintain energization of the solenoid 259a to hold the spring centered solenoid valve 258a in position delivering oil to the bottoms of the cylinders 169a so as to lift the wing 51a associated with these cylinders. It will also be observed that this lifting of the contact 284 of the switch 212a brings the movable contact 285 coupled therewith into engagement with the fixed contact 293. Accordingly, the apron 51, which was halted at its 15 angular elevation, again begins to rise, this being effected by the energization of its solenoid 259 through the circuit comprising the closed switch 260, wire 292, closed contacts 293 and 285 of the switch 212a, wire 286, solenoid 259 and line 262 through the solenoid 261 to the other side of the line. Accordingly, both aprons 51, 51a continue in their upward movement until stopped by the settings of their cams 209 as previously described.

It will accordingly be seen that the present invention provides a very simple, mechanism for insuring that neither apron 51 nor 51a can riseabove a selected angular position, such as the 15 position mentioned until the other wing has reached such position thereby to avoid imperfect work and possible injury to the mandrel.

What is claimed is:

1. In a brake for forming metal plate and sheet workpieces having a frame, a pair of forming aprons arranged in face-to-face relation on opposite sides of a plane which includes the forming axis about which the workpiece is to be formed and said aprons including working surfa es parallel and adjacent said forming axis, a clamping ram movable on said frame along said plane toward and from said working surfaces in opposed relation thereto, a mandrel carried by said clamping ram and having an exterior forming portion arranged to be brought into concentric relation with said forming axis by the movement of said clamping ram, and supporting pivot means on said frame concentric with said forming axis at opposite ends of said aprons; the combination therewith of means avoiding distortion of the work or mandrel as a consequence of one apron swinging beyond a predetermined minimum angular position before the other apron has reached such minimum angular position, comprising means severally swinging said aprons about said forming axis, and means responsive to the movement of each apron and controlling the movement of the other apron to compel both aprons to reach said minimum angular position jointly.

2. In a brake for forming metal plate and sheet workpieces having a frame, a pair of forming aprons arranged in face-to-face relation on opposite sides of a plane which includes the forming axis about which the workpiece is to be formed and said aprons including working surfaces parallel and adjacent said forming axis, a clamping ram movable on said frame along said plane toward and from said working surfaces in opposed relation thereto, a mandrel carried by said clamping ram and having an exterior forming portion arranged to be brought into concentric relation with said forming axis by the movement of said clamping ram, and supporting pivot means on said frame concentric with said forming axis at opposite ends of said aprons; the combination therewith of means avoiding distortion of the work or mandrel as a consequence of one apron swinging beyond a predetermined minimum angular position before the other apron has reached such minimum angular position, comprising means severally swinging said aprons about said forming axis, and means responsive to the movement of each apron and controlling the movement of the other apron to prevent movement of said other apron beyond said minimum angular position until the controlling apron reaches said minimum angular position.

3. In a brake for forming metal plate and sheet workpieces having a frame, a pair of forming aprons arranged in faee-to-face relation on opposite sides of a plane which includes the forming axis about which the workpiece is to be formed and said aprons including working surfaces parallel and adjacent said forming axis, a clamping ram movable on said frame along said plane toward and from said working surfaces in opposed relation thereto, a mandrel carried by said clamping ram and having an exterior forming portion arranged to be brought into concentric relation with said forming axis by the movement of said clamping ram, and supporting pivot means on said frame concentric with said forming axis at opposite ends of said aprons; the combination therewith of means avoiding distortion of the work or mandrel as a consequence of one apron swinging beyond a predetermined minimum angular position before the other apron has reached such minimum angular position, comprising means severally swinging said approns about said forming axis, means arranged to stop each of said aprons when it reaches said minimum angular position, and means actuated by each apron on reaching said minimum angular position and releasing said stop means of the other apron thereby to permit both aprons to swing beyond said minimum angular position.

4. In a brake for forming metal plate and sheet workpieces having a frame, a pair of forming aprons arranged in face-to-face relation on opposite sides of a plane which includes the forming axis about which the workpiece is to be formed and said aprons including working surfaces parallel and adjacent said forming axis, a clamping ram movable on said rame along said plane toward and from said worl-zinr surfaces in opposed, relation thereto, a man- 'drel carried by said clamping ram and having an exterior forming portion arranged to -be brought into concentric relation with said forming axis by the movement of said clamping ram, and supporting pivot means on said frame concentric with said forming axis at opposite ends of said aprons; the combination there-with of means avoiding distortion of the work or mandrel as a consequence of one apron swinging beyond a predetermined minimum angular position before the other apron has reached such minimum angular position, comprising hydraulic means swinging each of said aprons about said forming axis and including a solenoid valve controlling the flow of pressurized hydraulic fluid, first electrical switch means arranged to actuate each of said valves, second electrical switch means arranged to deactuate each of said valves first means responsive to the movement of one apron and actuating said second switch means to deactuate said one apron valve when said one apron reaches said minimum angular position, second means responsive to the movement of the other apron and actuating said second switch means to deactuate said other apron valve when said other apron reaches said minimum angular position, and third switch means arranged to reactu-ate both of said valves when both of said aprons reach said minimum angular position.

References Cited in the file of this patent UNITED STATES PATENTS 2,501,241 Shaw Mar. 21, 1950 2,651,349 Smith Sept. 9, 1953 2,716,436 Cady Apr. 30, 1955 

1. IN A BRAKE FOR FORMING METAL PLATE AND SHEET WORKPIECES HAVING A FRAME, A PAIR OF FORMING APRONS ARRANGED IN FACE-TO-FACE RELATION ON OPPOSITE SIDES OF A PLANE WHICH INCLUDES THE FORMING AXIS ABOUT WHICH THE WORKPIECE IS TO BE FORMED AND SAID APRONS INCLUDING WORKING SURFACES PARALLEL AND ADJACENT SAID FORMING AXIS, A CLAMPING RAM MOVABLE ON SAID FRAME ALONG SAID PLANE TOWARD AND FROM SAID WORKING SURFACES IN OPPOSED RELATION THERETO, A MANDREL CARRIED BY SAID CLAMPING RAM AND HAVING AN EXTERIOR FORMING PORTION ARRANGED TO BE BROUGHT INTO CONCENTRIC RELATION WITH SAID FORMING AXIS BY THE MOVEMENT OF SAID CLAMPING RAM, AND SUPPORTING PIVOT MEANS ON SAID FRAME CONCENTRIC WITH SAID FORMING AXIS AT OPPOSITE ENDS OF SAID APRONS; THE COMBINATION THEREWITH OF MEANS AVOIDING DISTORTION OF THE WORK OR MANDREL AS A CONSEQUENCE OF ONE APRON SWINGING BEYOND A PREDETERMINED MINIMUM ANGULAR POSITION BEFORE THE OTHER APRON HAS REACHED SUCH MINIMUM ANGULAR POSITION, COMPRISING MEANS SEVERALLY 